Valve service boxes, commonly known as curb boxes are well-known in the art. Modern valve boxes are generally fabricated of some suitable plastic, preferably ABS. The entire valve box generally comprises an upper portion having at least one pair of telescoping tubular members, the lowest tubular member having formed thereon at the bottom a hollow valve housing. A typical valve service box of this construction is illustrated in U.S. Pat. No. 3,601,143.
Recent developments in the art of underground pipes and valves have placed demands upon the structural and functional characteristics of valve service boxes not heretofor encountered. Public utilities have adopted the plastic or synthetic pipe instead of the metal pipe heretofor employed. However, until recently the valve body to which the pipe was attached continued to be fabricated of metal. The coupling of a plastic pipe to a metal valve body generated certain problems including torsional stress on the pipe. After a period of time, such torsional stresses spontaneously relieved by a rotation of the pipe which caused a corresponding rotation of the valve body displacing it from its normal vertical orientation. This in turn displaced the valve operating member from the usual vertical plane sometimes sufficiently so as to make extremely difficult, if not preclude, its actuation by the elongated actuating tool extending downwardly from the surface.
Most recently, the public utilities have adopted a valve fabricated of synthetic or plastic materials including a generally unitized valve body with a pair of integral inlet and outlet conduits. The pipe aforesaid is joined to the conduits by means of solvents forming a bond there between which involves the imposition of no torsional stresses on either member. However, the use of synthetic or plastic valves and valve bodies has generated additional problems.
The usual synthetic or plastic valve has a comparatively massive valve body which is structurally strong. Manufacturers recommend that the inlet and outlet conduits formed integrally with the valve body not be stressed by the application of a bearing load to the top or bottom thereof.
In the past, valve service housings or curb boxes have been structurally designed and employed such that the box imposed a vertical load on the extensions of the valve body to which the inlet and outlet pipes are connected. In the past, this was useful because the opening through which the valve body extensions extended were given a non-round or regular geometric configuration so as to restrain the valve body from rotation around the axis extending through the inlet and outlet conduits. This was effective to avoid the problem of plastic pipes relieving torsional stress in such a manner as to rotate the valve about said axis and thereby displace its actuating member from the vertical.
Accordingly, it is among the objects and advantages of the present invention to provide a valve service box with a hollow housing provided with internal bearing means adapted to engage the valve body to positively limit its upward movement in the housing such that the inlet and outlet conduits are vertically spaced away from the top of the openings through which they extend.
The most convenient and least costly method of fabricating the housing at the bottom of a valve service box is by blow-molding techniques employing a synthetic material such as ABS. Such blow molded synthetic housings are very substantially less rigid than a cast iron housing. Once a housing is in place over the valve, rotation of the housing about a vertical axis should be positively restrained. Otherwise, the inlet and outlet conduits will be bearing loaded from the side placing a stress upon the joint as well as the valve itself.
If the housing is formed in the shape of a generally radially enlarged cylindrical bell, there is little or no restraint against rotation about a vertical axis. Moreover, the side walls of such a housing are relatively weak particularly with the relatively large openings necessary to accommodate plastic valves.
Accordingly, it is among the further objects and advantages of the present invention to provide generally vertically extending flat wall portions on the housing which not only increase the rigidity of the housing wall and its vertical bearing load capabilities but also positively restrain the housing against rotation about a vertical axis.